1. Field of the Invention
The present invention generally relates to sports and hunting equipment and more particularly to an improved compound archery bow and a combination pulley and cam wheel for the same.
2. Prior Art
Compound archery bows have been devised to provide accurate shooting bows which have a lowered draw weight at full extension of the bowstring, in comparison with the draw weight necessary to pull the bowstring to the full draw position. This is accomplished by providing the bow with one or more cammed elements at one or both bow limb tips and/or at points therebetween.
When two or more cammed elements are used on the bow, the problem has been in properly adjusting the elements so that equal tension is applied to both bow limbs during drawing of the bowstring. Certain newer forms of compound archery bows have employed single cams at one end of the bow to avoid the just-described balancing problem. However, in most instances, torquing, that is, sideways twisting of one or both bow limbs has resulted, with consequential ultimate failure of the bow limbs and also less than desireable shooting characteristics for the compound bow.
A single cam compound archery bow is exemplified by that disclosed and claimed in U.S. Pat. No. 5,368,006. That bow utilizes a single long combination bowstring and return string which wraps around a top single track round pulley wheel and the opposite ends of which are connected to separate elements of a bottom cam. One of the difficulties with that bow is that when the string needs to be replaced, it is expensive and sometimes difficult to obtain a suitable substitute string, due to its unusually great length.
Moreover, commercial versions of the bow of that patent employ an anchor cable, one end of which is connected to the tip of the upper bow limb and the opposite end of which is connected to a grooved element on one side of the cam, the same side to which one end of the long combination bowstring and return string is attached. The opposite end of the combination bowstring and return string is attached to the main portion of the cam, which is aligned along the longitudinal axis of the bow. With this arrangement, when the bowstring is drawn, there is a torquing or twisting effect on the lower bow limb and to some extent also on the upper bow limb, with consequent strain on the bow.
Accordingly, there is a need for an improved type of compound archery bow which avoids all torquing of the bow limbs and which affords the archer an opportunity with the elements already installed on the bow of adjusting the bow for a two cam or one cam effect. There is also a need for a combination adjustable pulley and cam wheel device which can impart to the bow the described selective two or one cam effect. There is a further need for an improved compound archery having the described characteristics and which employs a bowstring of normal easily replaceable length.